Control method for electric thermostat and control apparatus thereof

ABSTRACT

Provided is a control method of an electric thermostat that can reduce cooling loss and friction loss of an engine by variably controlling opening/closing characteristic of the electric thermostat in accordance with metal surface temperature at a region with the maximum thermal load in the engine, can improve fuel efficiency by reducing the operation time and the number of operation times of a cooling fan of a radiator, and can improve heating performance for the interior of a vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Korean Patent Application Number 10-2010-0122042 filed Dec. 2, 2010, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a control method for an electric thermostat and a control apparatus thereof, and more particularly, to a technology of improving fuel efficiency, in addition to ensuring thermal stability of an engine, by appropriately controlling the temperature of the engine.

2. Description of Related Art

Electric thermostats, which compensate defects of mechanical thermostats having a function of merely opening/closing in accordance with a predetermined temperature in the related art, can more accurately control the temperature of an engine in accordance with the condition of the engine.

That is, the electric thermostats improve fuel efficiency by controlling temperature of cooling water of the engine at a relatively high level when the engine carries thermally small load, and ensure stability of the engine by controlling the temperature of the cooling water of the engine at a relatively low level when the engine carries thermally large load, such as a hill and rapid acceleration.

FIG. 1 shows an embodiment of an electric thermostat of the related art, in which a valve system 502 is disposed in a channel through which cooling water flows to open/close channel 500, similar to mechanical thermostats of the related art, and a heater 506 that generates heat by means of electricity supplied through a connector 504 and changes the opening/closing characteristic of valve system 502 is disposed in valve system 502.

One of methods of controlling the electric thermostat in the related art is to map what degree the opening temperature of the thermostat is set to in advance in a controller, through a test for four variables of external air temperature, load, vehicle speed, and cooling water temperature, and correspondingly perform control.

That is, it is possible to change the opening/closing characteristic of the thermostat by storing the map shown in FIG. 2 in the controller in advance and making voltage to supply to heater 506 different in accordance with load of a vehicle, even for the same cooling water temperature.

However, the control method is not easy to construct a map accurately reflecting the actual traveling conditions of the vehicle and also has a limit in constructing a map accurately and appropriately corresponding to all situations.

Further, conclusively, the main object of the thermostat is to ensure durability and stability of the engine by controlling metal surface temperature at a region with the maximum thermal load in the engine, not exceed a predetermined level, for example 200° C., however, it is difficult to achieve accurate control with the indirect control method using a map according to a plurality of variables, as described above, such that the map is constructed to achieve control in consideration of sufficient tolerance and accordingly there is a limit in improving fuel efficiency.

The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

SUMMARY OF INVENTION

Various aspects of the present invention provide for a control method and a control apparatus for an electric thermostat that can reduce cooling loss and friction loss of an engine by variably controlling opening/closing characteristic of the electric thermostat in accordance with metal surface temperature at a region with the maximum thermal load in the engine, can improve fuel efficiency by reducing the operation time and the number of operation times of a cooling fan of a radiator, and can improve heating performance for the interior of a vehicle.

Various aspects of the present invention provide for a control method of an electric thermostat comprising the steps of receiving that receives metal surface temperature at a region with the maximum thermal load of an engine, determining temperature that determines whether the metal surface temperature is within a plurality of temperature ranges that are sequentially set, and activating a thermostat that supplies different voltage for controlling an electric thermostat in accordance with the temperature ranges in which the received metal surface temperature is, after the determining temperature.

Other aspects of the present invention provide for a control apparatus of an electric thermostat, including a temperature input unit that receives the metal surface temperature at a region with the highest thermal load in an engine, a temperature determining unit that determines that which one of the sequentially set temperature ranges the metal surface temperature inputted through the temperature input unit pertains to, and a thermostat activating unit that supplies different voltage for controlling the electric thermostat.

According to various aspects of the present invention, it is possible to reduce cooling loss and friction loss of an engine by variably controlling opening/closing characteristic of the electric thermostat in accordance with metal surface temperature at a region with the maximum thermal load in the engine, can improve fuel efficiency by reducing the operation time and the number of operation times of a cooling fan of a radiator, and can improve heating performance for the interior of a vehicle, and a control apparatus of the electric thermostat.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an example of an electric thermostat according to the related art.

FIG. 2 is a diagram showing a map for controlling the electric thermostat according to the related art.

FIG. 3 is a flowchart illustrating an exemplary control method for an electric thermostat according to the present invention.

FIG. 4 is a block diagram showing an exemplary control apparatus of an electric thermostat according to the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

Referring to FIG. 3, various embodiments of the present invention includes receiving (S101) that receives metal surface temperature Te at a region with the maximum thermal load of an engine, determining temperature (S102) that determines whether the metal surface temperature is within a plurality of temperature ranges that are sequentially set, and activating a thermostat (S103) that supplies different voltage for controlling an electric thermostat in accordance with the temperature ranges in which the received metal surface temperature is, after the determining temperature (S102).

That is, the present invention can improve fuel efficiency of a vehicle, not by using indirect data, but by directly receiving metal surface temperature at a region with the maximum thermal load of an engine, and controlling the thermostat in accordance with the temperature to prevent thermal loss as much as possible through more accurate control.

The region with the maximum thermal load in the engine may be a cylinder liner adjacent to the engine combustion chamber, and for example, the temperature of the cylinder liner is directly measured and inputted.

In general, the temperature of the cylinder liners of common diesel engines are controlled between 180 to 200° C. for all sections where the engines operate and the temperature ranges are set in accordance with various embodiments of the present invention.

That is, referring to FIG. 3, the temperature range is divided into 180° C. or less, over 180° C. and 190° C. or less, over 180° C. and 200° C. or less, and over 200° C.

The electric thermostat is equipped with a heater, the opening/closing characteristic is changed by electricity supplied to the heater, and the electricity supplied to the heater is supplied differently in accordance with the temperature range in which the received metal surface temperature is, in the activating a thermostat (S103).

In various embodiments, after the receiving (S101), the determining temperature (S102) and the activating a thermostat (S103) are alternately performed sequentially from the lower temperature range to the higher temperature range in the temperature ranges.

That is, after the metal surface temperature is inputted in the receiving (S101), it is determined that the metal surface temperature is 180° C. or less, and then 0V voltage is supplied to the heater when the temperature is in the range, 4V voltage is supplied to the heater when the metal surface temperature Te is 180° C.<Te≦190° C., 8V voltage is supplied to the heater when the metal surface temperature Te is 190° C.<Te≦2000° C., and 12V voltage is supplied to the heater when the metal surface temperature Te is Te<200° C.

In this configuration, the higher the voltage supplied to the heater, the lower the opening temperature of the thermostat. Accordingly, when the metal surface temperature is the lowest, 0V voltage is supplied, that is, electricity is not supplied, such that the opening temperature reaches 105° C. only by the mechanical properties of the thermostat itself, however, when the metal surface temperature is high, that is, 200° C. or more, the highest voltage of 12V is supplied to the heater of the thermostat such that the thermostat can be opened even at 80° C., thereby achieve rapid cooling.

Obviously, after the receiving (S101), the determining temperature (S102) and the activating a thermostat (S103) may be performed in the reverse order, that is, alternately performed sequentially from the higher temperature range to the lower temperature range in the temperature ranges.

As described above, by directly receiving metal surface temperature at the most vulnerable portion to the thermal load of the engine and making the voltage supplied to the electric thermostat different, it is possible to limit the temperature of the vulnerable portion of the engine to the thermal load in a stable level. Further, it is possible to ensure sufficient durability against the thermal load of the engine, minimize cooling loss, and improve fuel efficiency by reducing friction loss, and the operation time and the number of operation times of the cooling fan of a radiator.

Further, the cooling water for the engine can be kept at relatively high temperature in comparison to the related art, such that it is possible to improve heating performance for the interior.

A control apparatus of an electric thermostat according to various embodiments of the present invention, for implementing the control method described above, includes a temperature input unit 10 that receives the metal surface temperature at a region with the highest thermal load in an engine, a temperature determining unit 12 that determines that which one of the sequentially set temperature ranges the metal surface temperature inputted through temperature input unit 10 pertains to, and a thermostat activating unit 16 that supplies different voltage for controlling electric thermostat 14 in accordance with the temperature range determined by temperature determining unit 12.

Therefore, the metal surface temperature directly measured from the region with the high thermal load in the engine is inputted through temperature input unit 10, the temperature determining unit 12 determines that which temperature range in the pre-stored temperature ranges the received metal surface temperature pertains to, and the thermostat activating unit 16 supplies electricity set for the determined temperature range to electric thermostat 14, such that the temperature of the cooling water for the engine is rapidly and appropriately controlled.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. A control method of an electric thermostat, comprising the steps of: receiving that receives a metal surface temperature at a region with a maximum thermal load of an engine; determining temperature that determines whether the metal surface temperature is within a plurality of temperature ranges that are sequentially set; and activating a thermostat that supplies different voltage for controlling an electric thermostat in accordance with the temperature ranges in which the received metal surface temperature is, after the determining temperature.
 2. The method as defined in claim 1, wherein after the receiving step, the determining temperature step and the activating a thermostat step are alternately performed sequentially from the lower temperature range to the higher temperature range in the temperature ranges.
 3. The method as defined in claim 1, wherein after the receiving step, the determining temperature step and the activating a thermostat step are alternately performed sequentially from the higher temperature range to the lower temperature range in the temperature ranges.
 4. The method as defined in claim 1, wherein the electric thermostat is equipped with a heater and different voltages are supplied to the heater in accordance with the temperature range in which the received metal surface temperature is, in the activating a thermostat step.
 5. A control apparatus of an electric thermostat, comprising: a temperature input unit that receives the metal surface temperature at a region with the highest thermal load in an engine; a temperature determining unit that determines that which one of the sequentially set temperature ranges the metal surface temperature inputted through the temperature input unit pertains to; and a thermostat activating unit that supplies different voltage for controlling the electric thermostat. 